LED element with an inverted taper structure for minimizing a defect rate of electrode connections, and display device using the same

ABSTRACT

A light-emitting device and a display including the same can improve the process stability during the process of disposing the light-emitting device. A light-emitting device includes the n-type semiconductor layer and the p-type semiconductor layer, and a structure is disposed so as to minimize electrical short between electrodes even if the light-emitting device is misaligned. The structure may have at least one side surface in an inverted taper shape and may be disposed between electrodes to minimize a short-circuit therebetween during the process of connecting the electrodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.10-2017-0167546 filed on Dec. 7, 2017, in the Korean IntellectualProperty Office, the disclosure of which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a light-emitting device and a displaydevice using the same, and more particularly, to a light-emitting devicewith improved efficiency of electrode connection and stability of wiringconnection in electrically connecting the light-emitting device with thewiring electrodes, thereby increasing the reliability of the device, anda display device using the same.

DESCRIPTION OF THE RELATED ART

A display device is widely used as display screens of a notebookcomputer, a tablet computer, a smart phone, a portable display deviceand a portable information device, in addition to display devices of atelevision or a monitor.

Display devices may be divided into a reflective display device and alight-emitting display device. The reflective display device displaysinformation as natural light or light emitted from an external luminaireis reflected off the display device. The light-emitting display deviceincludes a light-emitting device or a light source therein and displaysinformation by using the light emitted from the light-emitting device orthe light source.

The light-emitting device may use a light-emitting device capable ofemitting various wavelengths of light, or may use a light-emittingdevice emitting white or blue light together with a color filter capableof changing the wavelength of emitted light.

As described above, in order to display an image on a display device, aplurality of light-emitting devices is disposed on a substrate of thedisplay device. In order to control each light-emitting device to emitlight individually, a driving element for supplying a driving signal ora driving current is disposed on the substrate together with thelight-emitting device. The plurality of light-emitting devices disposedon the substrate is analyzed according to the arrangement of informationto be displayed, to display the information on the substrate.

In other words, the plurality of pixels is disposed in the displaydevice, and each of the pixels uses a thin-film transistor as aswitching element which is a driving element. Each of the pixels isconnected to the thin-film transistor and is driven, so that the displaydevice displays images as the pixels are operated individually.

Representative display devices using thin-film transistors include aliquid-crystal display device and an organic light-emitting displaydevice. Among them, a liquid-crystal display device is not aself-luminous display device, and thus it requires a backlight unitdisposed under (behind) the liquid-crystal display device to emit light.Such a backlight unit increases the thickness of the liquid-crystaldisplay device. In addition, it is not possible to implement a displaydevice having a variety of shapes such as a flexible or circular displaydevice with such a backlight unit. Moreover, the luminance and responsespeed may be lowered.

On the other hand, a display device having a self-luminous element canbe made thinner than a display device having a light source, and isadvantageous for a flexible and foldable display device.

Such a display device having a self-luminous element may be divided intoan organic light-emitting display device including an organic materialas an emission layer, and a micro-LED display device using a micro-LEDelement as a light-emitting device. Such a self-luminous display device,such as an organic light-emitting display device and a micro-LED displaydevice, does not require an additional light source, and thus can beused for thin display devices having various shapes.

However, even though an organic light-emitting display device using anorganic material does not require an additional light source, there is aproblem that a defective pixel may occur due to moisture and oxygen.Accordingly, a variety of technical ideas are additionally required tominimize permeation of oxygen and moisture.

Regarding the above-mentioned problem, research and development on adisplay device using a micro-sized micro light-emitting diode as alight-emitting device have been progressed recently. Such alight-emitting display device has attracted attention as anext-generation display device because of its high image quality andhigh reliability.

An LED element is a semiconductor light-emitting device utilizing theproperty that light is emitted when a current flows in a semiconductordevice. Such LED elements are widely employed by luminaires, TVs, avariety of display devices, etc. An LED element is composed of an n-typesemiconductor layer, a p-type semiconductor layer, and an active layertherebetween. When a current flows, electrons in the n-typesemiconductor layer and holes in the p-type semiconductor layerrecombine in the active layer to emit light.

The LED element is composed of a compound semiconductor such as GaN, andcan inject a high current due to the property of the inorganic material,thereby achieving a high luminance. In addition, the LED element hashigh reliability since it is less affected by the environment such asheat, moisture and oxygen.

In addition, the LED element has an internal quantum efficiency of about90%, which is higher than that of organic light-emitting displaydevices. Therefore, there are advantages that it can display highluminance images and consume less power.

Further, unlike organic light-emitting display devices, the influence byoxygen and moisture is ignorable in using an inorganic material.Therefore, no additional encapsulation layer or substrate for minimizingpermeation of moisture and oxygen is required, and thus it is possibleto reduce the inactive area of the display device which is a margin areawhere an encapsulation layer or substrate is disposed.

After a light-emitting device such as an LED element is formed on aseparate substrate, a process of transplanting it to a display devicemay be necessary. In order to provide the display device having theadvantages as described above, there are required a technique ofdisposing the light-emitting device at a correct location on the displaydevice, and a technique minimizing errors that may occur during theprocess of disposing the light-emitting device. There are many researchactivities on this.

SUMMARY

As mentioned above, there are several technical requirements forimplementing a light-emitting display device employing an LED element asa light-emitting device of a unit pixel. Initially, LED elements arecrystallized on a semiconductor wafer substrate such as sapphire orsilicon (Si), and the crystallized LED elements are moved to a substratewhere a driving element is disposed. In doing so, a sophisticatedtransfer process for positioning the LED elements at locationscorresponding to the respective pixels is required.

Although the LED element may be formed using an inorganic material, itis necessary to crystallizing them. In order to crystallize an inorganicmaterial such as GaN, the inorganic material has to be crystallized on asubstrate capable of inducing crystallization. The substrate capable ofefficiently inducing crystallization of the inorganic material is asemiconductor substrate. The inorganic material has to be crystallizedon the semiconductor substrate as described above.

The process of crystallizing the LED element is also referred to asepitaxy, epitaxial growth or epitaxial process. An epitaxial processrefers to growing a film on the surface of a crystal with a specificorientation relationship. In order to form the device structure of anLED element, a GaN compound semiconductor has to be stacked on thesubstrate in the form of a pn junction diode. At this time, each layeris grown by inheriting the crystallinity of the underlying layer.

A defect inside the crystal acts as a nonradiative center in theelectron-hole recombination process. Therefore, in an LED device usingphotons, the crystallinity of the crystals forming each layer has agreat influence on the device efficiency.

Currently, the sapphire substrate is commonly used as the substratemainly. Recently, research is ongoing into GaN-based substrates.

The price of the semiconductor substrate required for crystallizing theinorganic material such as GaN constituting the LED element on thesemiconductor substrate is high. Therefore, when a large amount of LEDsare used as light-emitting pixels of a display device, rather than LEDsas a light source used for simple luminaire or a backlight unit, thereis a problem that the production cost is increased.

In addition, as described above, the LED element formed on thesemiconductor substrate requires a step of transferring it to thesubstrate of a display device. In doing so, it is difficult to separatethe LED element from the semiconductor substrate. Furthermore, it ismore difficult to transplant the separated LED element to a designedlocation correctly.

In transferring the LED element formed on the semiconductor substrate toa substrate for implementing a display device, a variety of transferringmethod may be available, including a method of using a polymer-materialbased substrate for transferring such as PDMS, a method of transferringusing an electromagnetic force or electrostatic force, or a method ofpicking and moving one by one, etc.

Such a transfer process is related to the productivity of the process offabricating display devices, and thus it would be inefficient totransfer the LED elements one by one for mass production.

Accordingly, a precise transfer process or technique is required inorder to separate a plurality of LED elements from a semiconductorsubstrate using a substrate for transfer made of a polymer material tolocate them to a substrate of a display device, especially on a padelectrode connected to a driving element and a power electrode disposedin a thin-film transistor.

During the above-described transferring process or subsequent processesthat follow the transferring process, there may be defects, e.g., theLED element is flipped over while it is moved or transferred dependingon conditions such as vibration or heat. There were many difficulties infinding and recovering such defects.

Hereinafter, the defects will be described in more detail with referenceto a general transfer process as an example.

First, an LED element is formed on a semiconductor substrate, and anelectrode is formed thereon, so that an individual LED element iscompleted. Subsequently, the semiconductor substrate is brought intocontact with the PDMS substrate (hereinafter referred to as a transfersubstrate). In this process, the LED elements have to be transferredfrom the semiconductor substrate to the transfer substrate taking intoaccount the pixel pitch among the pixels of the actual displaysubstrate. Therefore, when the transfer substrate has protruded featuresor the like for receiving the LED elements, the protruded features orthe like has to be disposed considering the pixel pitch.

Subsequently, a laser is irradiated onto the LED elements through theback surface of the semiconductor substrate, thereby separating the LEDelements from the semiconductor substrate. In the process of irradiatingthe laser, when the LED element is separated from the semiconductorsubstrate, the GaN material of the semiconductor substrate may bephysically and rapidly expanded due to concentration of the high energyof the laser, possibly resulting in shock. As a result, when the LEDelements are transferred to the transfer substrate, the LED elements maybe pushed such that it may be transferred to an undesirable location.(This is referred to as primary transfer.)

Subsequently, the LED elements transferred onto the transfer substrateare transferred onto the substrate of the display device. A passivationlayer for insulating/protecting a thin-film transistor is disposed on asubstrate, and then an adhesive layer is disposed on the passivationlayer.

When the transfer substrate is brought into contact with the substrateof the display device to receive pressure, the LED elements transferredonto the transfer substrate are transferred to the substrate of thedisplay device by the adhesive layer on the passivation layer.

If the adhesive force between the transfer substrate and the LEDelements is smaller than the adhesive force between the substrate of thedisplay device and the LED element, the LED elements on the transfersubstrate can be transferred to the substrate of the display device.(This is referred to as secondary transfer).

The size of the semiconductor substrate is basically different from, andtypically smaller than the size of the substrate of the display device.Due to such difference in area and size, the above-described primary andsecondary transfer processes are repeated by dividing the substrate ofthe display device into sub-areas, so that the LED elements can betransferred to the display device.

In the process of repeating the primary transfer and the secondarytransfer, the LED elements can be transferred to an undesirablelocation. Various errors may occur depending on the number of transferprocesses or the process variation of the transfer processes.

The LED elements formed on the semiconductor substrate may be red, blueand green LED elements depending on the type thereof, or may be a whiteLED element. In the method of implementing pixels of a display deviceusing LED elements emitting light of different wavelengths, the numberof times of the primary and secondary transfer processes described abovemay be further increased.

The LED elements may be flipped over or rotated in the primary andsecondary transfer processes, as described above. This increases thenumber of defective pixels of the display device and increasesproduction cost. In view of the above, the inventors of the applicationhave devised an LED element which is a light-emitting device capable ofbeing disposed more stably, and a display device using the same.

Accordingly, embodiments of the present disclosure are directed to alight-emitting device and a display device using the same thatsubstantially obviate one or more of the problems due to limitations anddisadvantages of the related art.

An object of the present disclosure is to provide a light-emittingdevice capable of minimizing defect rate of display devices by way ofelectrically connecting a light-emitting device even if it is misalignedaway from a location during a process of transferring and disposing thelight-emitting device.

It should be noted that objects of the present disclosure are notlimited to the above-described objects, and other objects of the presentdisclosure will be apparent to those skilled in the art from thefollowing descriptions.

Additional features and aspects will be set forth in the descriptionthat follows, and in part will be apparent from the description, or maybe learned by practice of the inventive concepts provided herein. Otherfeatures and aspects of the inventive concepts may be realized andattained by the structure particularly pointed out in the writtendescription, or derivable therefrom, and the claims hereof as well asthe appended drawings.

To achieve these and other aspects of the inventive concepts, asembodied and broadly described, a light-emitting device is provided thatcan be disposed stably, and a display device including the same areprovided. The light-emitting device may include an n-type semiconductorlayer and a p-type semiconductor layer. An n-type electrode is disposedon the n-type semiconductor layer, and a p-type electrode is disposed onthe p-type semiconductor layer. A structure may be disposed between then-type electrode and the p-type electrode. The structure may have atleast one side surface in an inverted taper shape adjacent to the p-typeelectrode or the n-type electrode.

In this manner, an inverted tapered structure is disposed between then-type electrode and the p-type electrode, to minimize a defect that thetwo electrodes are electrically connected during the process ofconnecting the p-type electrode and the n-type electrode to the pixelelectrode or the common electrode. As a result, it is possible tominimize the defect rate of the display device by minimizing thedefective connection of the electrodes even if the light-emitting deviceis misaligned during the process of disposing it.

According to an exemplary embodiment of the present disclosure, alight-emitting device having a structure that can improve processingstability to dispose the light-emitting device is employed, so thatdefects of display devices can be reduced while productivity can beimproved. In addition, by employing the light-emitting device,processing convenience can be improved.

It should be noted that effects of the present disclosure are notlimited to those described above and other effects of the presentdisclosure will be apparent to those skilled in the art from thefollowing descriptions.

The Summary is not to specify essential features of the appended claims,and thus the scope of the claims is not limited thereby.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the inventive concepts asclaimed

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated and constitute apart of this application, illustrate embodiments of the disclosure andtogether with the description serve to explain various principles. Inthe drawings:

FIG. 1 is a schematic plan view of a light-emitting device according toan exemplary embodiment of the present disclosure;

FIG. 2 is a circuit diagram for illustrating a configuration of a unitpixel according to the exemplary embodiment shown in FIG. 1;

FIG. 3 is a cross-sectional view illustrating an arrangement of alight-emitting device according to an exemplary embodiment of thepresent disclosure and connection of electrodes;

FIGS. 4A and 4B are plan views illustrating a light-emitting deviceaccording to an exemplary embodiment of the present disclosure;

FIGS. 5A and 5B are views for illustrating connection of electrodes ofan light-emitting device according to an exemplary embodiment of thepresent disclosure; and

FIGS. 6A to 6D are cross-sectional views for illustrating electrodeconnection of a light-emitting device according to various exemplaryembodiments of the present disclosure.

DETAILED DESCRIPTION

Advantages and features of the present disclosure and methods to achievethem will become apparent from the descriptions of exemplary embodimentshereinbelow with reference to the accompanying drawings. However, thepresent disclosure is not limited to exemplary embodiments disclosedherein but may be implemented in various different ways. The exemplaryembodiments are provided for making the disclosure of the presentdisclosure thorough and for fully conveying the scope of the presentdisclosure to those skilled in the art. It is to be noted that the scopeof the present disclosure is defined only by the claims.

The figures, dimensions, ratios, angles, the numbers of elements givenin the drawings are merely illustrative and are not limiting. Likereference numerals denote like elements throughout the descriptions.Further, in describing the present disclosure, descriptions onwell-known technologies may be omitted in order not to unnecessarilyobscure the gist of the present disclosure. It is to be noticed that theterms “comprising,” “having,” “including” and so on, used in thedescription and claims, should not be interpreted as being restricted tothe means listed thereafter unless specifically stated otherwise. Wherean indefinite or definite article is used when referring to a singularnoun, e.g. “a,” “an,” “the,” this includes a plural of that noun unlessspecifically stated otherwise.

In describing elements, they are interpreted as including error marginseven without explicit statements.

In describing positional relationship, such as “an element A on anelement B,” “an element A above an element B,” “an element A below anelement B” and “an element A next to an element B,” another element Cmay be disposed between the elements A and B unless the term “directly”or “immediately” is explicitly used.

In describing temporal relationship, terms such as “after,” “subsequentto,” “next to” and “before” are not limited to “directly after,”“directly subsequent to,” “immediately next to” “immediately before,”and so on, unless otherwise specified.

In describing flow of signals, such as “a signal is delivered from nodeA to node B,” a signal may be delivered from node A to node B viaanother node unless the term “directly” or “immediately” is explicitlyused.

The terms first, second, third and the like in the descriptions and inthe claims are used for distinguishing between similar elements and notnecessarily for describing a sequential or chronological order. Thesesterms are used to merely distinguish one element from another.Accordingly, as used herein, a first element may be a second elementwithin the technical idea of the present disclosure.

Features of various exemplary embodiments of the present disclosure maybe combined partially or totally. As will be clearly appreciated bythose skilled in the art, technically various interactions andoperations are possible. Various exemplary embodiments can be practicedindividually or in combination.

Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a plan view of a light-emitting display device according to anexemplary embodiment of the present disclosure. FIG. 2 is a circuitdiagram for illustrating a configuration of a unit pixel according tothe exemplary embodiment shown in FIG. 1. Referring to FIGS. 1 and 2, alight-emitting display device 100 according to the exemplary embodimentof the present disclosure includes a substrate 110 on which an activearea AA where a plurality of unit pixels UP is disposed, and an inactivearea IA are defined.

Each of the unit pixels UP may include a plurality of sub-pixels SP1,SP2 and SP3 on a front face 110 a of the substrate 110. Although thesub-pixels SP1, SP2 and SP3 typically may emit red, blue and greenlight, respectively, this is not limiting. For example, the sub-pixelsmay include a sub-pixel emitting white light.

The substrate 110 may be a thin-film transistor array substrate made ofglass or a plastic material. It may be formed by attaching two or moresubstrates together or by stacking two or more layers. The inactive areaIA may be defined as a region on the substrate 110 except for the activearea AA, which may have a relatively very small width and may be definedas a bezel area.

The plurality of unit pixels UP is disposed in the active area AA. Theunit pixels UP are arranged in the active area AA such that they have apredetermined first reference pixel pitch along the x-axis direction andhave a predetermined second reference pixel pitch along the y-axisdirection. The first reference pixel pitch may be defined as thedistance between the centers of adjacent unit pixels UP. The secondreference pixel pitch may be defined as the distance between the centersof adjacent unit pixels UP in the reference direction, similar to thefirst reference pixel pitch.

The distance among the sub-pixels SP1, SP2 and SP3 of each unit pixel UPmay also be defined as a first reference sub-pixel pitch and a secondreference sub-pixel pitch, similar to the first reference pixel pitchand the second reference pixel pitch.

In the light-emitting display device 100 including an LED element 150 asan LED element, the width of the inactive area IA may be smaller thanthe pixel pitches or the sub-pixel pitches described above. When amulti-screen display device is implemented with the light-emittingdisplay device 100, the width of the inactive area IA is smaller thanthe pixel pitches or the sub-pixel pitches, and thus it is possible toimplement a multi-screen display device having substantially no bezelarea.

In order to implement such a multi-screen display device with no orsubstantially no bezel area, the first reference pixel pitch, a secondreference pixel pitch, the first reference sub-pixel pitch and thesecond reference sub-pixel pitch may be maintained constant in theactive area of the light-emitting display device 100. Alternatively, bydividing the active area AA into several sub-areas so that differentsub-areas have different pitches, and by making the pixel pitches of thesub-areas adjacent to the inactive area IA are larger than those of theother sub-areas, the size of the bezel area can be made smaller than thepixel pitches.

In the light-emitting display device 100 having different pixel pitches,distortion of images may occur. To overcome it, image processing isperformed in such a manner that image data is sampled in comparison withadjacent areas in consideration of the pixel pitches. By doing so, thebezel area can be reduced while minimizing the distortion of the image.

However, in reducing the size of the inactive area IA, the minimum areais required for a pad area for connecting to circuitry that suppliespower to and transmits/receives data signals to/from the unit pixels UPhaving the LED elements 150, and an area for a drive IC, etc.

The configuration and circuit structure of the sub-pixels SP1, SP2 andSP3 of each of the unit pixels UP of the light-emitting display device100 will be described with reference to FIG. 2. Pixel drive lines areprovided on the front surface 110 a of the substrate 110 and supplynecessary signals to each of the plurality of sub-pixels SP1, SP2, andSP3. According to the exemplary embodiment of the present disclosure,the pixel drive lines include a plurality of gate lines GL, a pluralityof data lines DL, a plurality of driving power lines DPL, and aplurality of common power lines CPL.

The plurality of gate lines GL is disposed on the front face 110 a ofthe substrate 110 and is extended in a first horizontal axis direction Xof the substrate 110 while being spaced apart from one another in asecond horizontal axis direction Y.

The plurality of data lines DL is disposed on the front face 110 a ofthe substrate 110 such that they intersect with the gate lines GL and isextended in the second horizontal axis direction Y of the substrate 110while being spaced apart from one another in the first horizontal axisdirection X.

The driving power lines DPL are disposed on the substrate 110 such thatthey are parallel to the data lines DL and may be formed together withthe data lines DL. Each of the driving power lines DPL supplies a pixeldrive power provided from an external source to the adjacent sub-pixelsSP.

The common power lines CPL are disposed on the substrate 110 such thatthey are parallel to the gate lines DL and may be formed together withthe gate lines GL. Each of the common power lines CPL supplies a commonpower provided from an external source to the adjacent sub-pixels SP1,SP2 and SP3.

Each of the plurality of sub-pixels SP1, SP2 and SP3 is disposed in asub-pixel region defined by the respective gate lines GL and data linesDL. Each of the plurality of sub-pixels SP1, SP2, and SP3 may be definedas a minimum unit region from which light is actually emitted.

At least three sub-pixels SP1, SP2 and SP3 adjacent to one another mayform a single unit pixel UP for representing a color. For example, asingle unit pixel UP may include a red sub-pixel SP1, a green sub-pixelSP2 and a blue sub-pixel SP3 adjacent to one another along the firsthorizontal axial direction X and may further include a white sub-pixelto improve the luminance.

Optionally, each of the plurality of driving power lines DPL may bedisposed in the respective unit pixels UP. Then, at least threesub-pixels SP1, SP2 and SP3 of each of the unit pixels UP share onedriving power line DPL. As a result, it is possible to reduce the numberof driving power lines for driving the sub-pixels SP1, SP2 and SP3, sothat the aperture ratio of each unit pixel UP can be increased by thenumber of reduced driving power lines, or the size of each unit pixel UPcan be reduced.

Each of the plurality of sub-pixels SP1, SP2 and SP3 according to anexemplary embodiment of the present disclosure includes a pixel circuitPC and an LED element 150.

The pixel circuit PC is disposed in a circuit region defined in each ofthe sub-pixels SP and is connected to the adjacent gate line GL, dataline DL and driving power line DPL. The pixel circuit PC controls acurrent flowing through the LED element 150 according to a data signalfrom the data line DL in response to a scan pulse from a gate line GLbased on a pixel drive power supplied from the driving power line DPL.According to an exemplary embodiment of the present disclosure, thepixel circuit PC includes a switching thin-film transistor T1, a drivingthin-film transistor T2, and a capacitor Cst.

The switching thin-film transistor T1 includes a gate electrodeconnected to a gate line GL, a first electrode connected to a data lineDL, and a second electrode connected to a gate electrode N1 of thedriving thin-film transistor T2. The first and second electrodes of theswitching thin-film transistor T1 may be a source electrode and a drainelectrode or vice versa depending on the current direction. Theswitching thin-film transistor T1 is switched on/off in response to ascan pulse supplied to the gate line GL to supply a data signal suppliedto the data line DL to the driving thin-film transistor T2.

The driving thin-film transistor T2 is turned on by the voltage suppliedfrom the switching thin-film transistor T1 and/or the voltage of thecapacitor Cst, to control the amount of the current flowing from thedriving power line DPL to the LED element 150. To this end, the drivingthin-film transistor T2 according to an exemplary embodiment of thepresent disclosure includes a gate electrode connected to the secondelectrode N1 of the switching thin-film transistor T1, a drain electrodeconnected to the driving power line DPL, and a source electrodeconnected to the LED element 150. The driving thin-film transistor T2controls the data current flowing from the driving power line DPL to theLED element 150 based on the data signal supplied from the switchingthin-film transistor T1, to control the emission of the LED element 150.

The capacitor Cst is disposed in an area where the gate electrode N1 andthe source electrode of the driving thin-film transistor T2 overlapswith each other, and stores a voltage corresponding to a data signalsupplied to the gate electrode of the driving thin-film transistor T2,to turn on the driving thin-film transistor T2 with the stored voltage.

Optionally, the pixel circuit PC may further include at least onecompensating thin-film transistor for compensating for a change in thethreshold voltage of the driving thin-film transistor T2, and mayfurther include at least one auxiliary capacitor. The pixel circuit PCmay further receive a compensating power such as an initializing voltagedepending on the numbers of the thin-film transistors and the auxiliarycapacitors. Accordingly, the pixel circuit PC according to the exemplaryembodiment of the present disclosure drives the LED element 150 bycurrent driving manner like the sub-pixels of an organic light-emittingdisplay device, and thus the pixel circuit PC can be adapted for a pixelcircuit of an organic light-emitting display device known in the art.

The LED element 150 is disposed in each of the plurality of sub-pixelsSP1, SP2 and SP3. The LED element 150 is electrically connected to thepixel circuit PC of the sub-pixel SP and the common power line CPL sothat it emits light as the current flows therethrough from the pixelcircuit PC, i.e., the driving thin-film transistor T2 to the commonpower line CPL. The LED element 150 according to an exemplary embodimentof the present disclosure may be an optical element or a light-emittingdiode chip that emits one of red light, green light, blue light, andwhite light. The light-emitting diode chip may have, but is not limitedto, a scale of 1 to 100 micrometers. The chip may have a size smallerthan the size of the remaining emission region excluding the circuitarea occupied by the pixel circuit PC in the sub-pixel area.

FIG. 3 is a cross-sectional view illustrating an arrangement of alight-emitting device according to an exemplary embodiment of thepresent disclosure and connection of electrodes. Description will bemade with reference to FIG. 3 in conjunction with FIGS. 1 and 2.

Each of the sub-pixels SP1, SP2 and SP3 of the display device accordingto an exemplary embodiment of the present disclosure includes apassivation layer 113, an LED element 150, planarization layers 115-1and 115-2, a pixel electrode PE, and a common electrode CE.

Although the substrate 110 is shown as being relatively thin in FIG. 3,the substrate 110 may be much thicker than the overall thickness of thelayer structure formed on the substrate 110. The substrate 110 may bemade up of a plurality of layers or may be formed by attaching aplurality of substrates together.

The pixel circuit PC includes a switching thin-film transistor T1, adriving thin-film transistor T2, and a capacitor C. The pixel circuit PCis identical to that described above; and, therefore, the redundantdescription will be omitted. Hereinafter, the structure of the drivingthin-film transistor T2 will be described by way of example.

The driving thin-film transistor T2 includes a gate electrode GE, asemiconductor layer SCL, a source electrode SE, and a drain electrodeDE.

The gate electrode GE is disposed on the substrate 110 together with thegate line GL. The gate electrode GE is covered by the gate insulatinglayer 112. The gate insulating layer 112 may be made up of a singlelayer or multiple layers made of inorganic material, for example,silicon oxide (SiOx) and silicon nitride (SiNx).

The semiconductor layer SCL is disposed on the gate insulating layer 112in a predetermined pattern (or in the form of an island) such that itoverlaps with the gate electrode GE. The semiconductor layer SCL may bemade of, but is not limited to, a semiconductor material composed of oneof amorphous silicon, polycrystalline silicon, oxide, and organicmaterial.

The source electrode SE is disposed such that it overlaps with one sideof the semiconductor layer SCL. The source electrode SE is disposedtogether with the data line DL and the driving power line DPL.

The drain electrode DE is disposed such that it overlaps with the otherside of the semiconductor layer SCL and spaced apart from the sourceelectrode SE. The drain electrode DE is disposed together with thesource electrode SE and branches off or protrudes from an adjacentdriving power line DPL.

In addition, the switching thin-film transistor T1 of the pixel circuitPC is disposed with the same structure as the driving thin-filmtransistor T2. At this time, the gate electrode of the switchingthin-film transistor T1 branches off or protrudes from the gate line GL.The first electrode of the switching thin-film transistor T1 branchesoff or protrudes from the data line DL. The second electrode of theswitching thin-film transistor T1 is connected to the gate electrode GEof the driving thin-film transistor T2 through a via hole formed in thegate insulating layer 112.

The passivation layer 113 is formed over the entire surface of thesubstrate 110 such that it covers the sub-pixel SP, i.e., the pixelcircuit PC. The passivation layer 113 protects the pixel circuit PC andprovides a flat surface. The passivation layer 113 may be made of anorganic material such as benzocyclobutene or photo-acryl. Preferably,the passivation layer 113 may be made of a photo-acrylic material forconvenience of process.

The LED element 150 according to an exemplary embodiment of the presentdisclosure may be disposed on the passivation layer 113 by using anadhesive member 114. Alternatively, the LED element 150 may be disposedin a recess formed in the passivation layer 113. When the LED element150 is disposed in the recess, an inclined surface of the recess in thepassivation layer 113 may lead the light emitted from the LED element150 in a particular direction to improve the luminous efficiency.

The LED element 150 is electrically connected to the pixel circuit PCand the common power line CPL so that it emits light as the currentflows therethrough from the pixel circuit PC, i.e., the drivingthin-film transistor T2 to the common power line CPL. The LED element150 according to an exemplary embodiment of the present disclosureincludes an emission layer EL, a first electrode (or an anode terminal)E1, and a second electrode (or a cathode terminal) E2.

The LED element 150 emits light as electrons and holes recombineaccording to the current flowing between the first electrode E1 and thesecond electrode E2.

The planarization layers 115-1 and 115-2 are disposed on the passivationlayer 113 such that it covers the LED element 150. Specifically, theplanarization layers 115-1 and 115-2 are disposed on the passivationlayer 113 with a sufficient thickness to cover the entire surface of thepassivation layer 113, i.e., the LED element 150 and the rest of thefront surface.

The planarization layers 115-1 and 115-2 may be made up of a singlelayer. Alternatively, the planarization layers 115-1 and 115-2 may bemade up of multi-layer structure including the first planarization layer115-1 and the second planarization layer 115-2, as shown in thedrawings.

The planarization layers 115-1 and 115-2 provide a flat surface over thepassivation layer 113. In addition, the planarization layers 115-1 and115-2 serve to fix the position of the LED element 150.

The pixel electrode PE connects the first electrode E1 of the LEDelement 150 to the drain electrode DE of the driving thin-filmtransistor T2. The first electrode E1 may be connected to the sourceelectrode SE depending on the configuration of the thin-film transistorT2. The pixel electrode PE may be defined as an anode electrode. Thepixel electrode PE according to an exemplary embodiment of the presentdisclosure is disposed on the front surfaces of the planarization layers115-1 and 115-2 overlapping the first electrode E1 of the LED element150 and the driving thin-film transistor T2. The pixel electrode PE iselectrically connected to the drain electrode DE or the source electrodeof the driving thin-film transistor T2 through a first circuit contacthole CCH1 formed in the passivation layer 113 and the planarizationlayers 115-1 and 115-2, and is electrically connected to the firstelectrode E1 of the LED element 150 through an electrode contact holeECH formed in the planarization layers 115-1 and 115-2. Accordingly, thefirst electrode E1 of the LED element 150 is electrically connected tothe drain electrode DE or the source electrode SE of the drivingthin-film transistor T2 through the pixel electrode PE.

Although the drain electrode DE is connected to the pixel electrode PEin the foregoing description, the source electrode SE may also beconnected to the pixel electrode PE, as desired by those skilled in theart.

The pixel electrode PE may be made of a transparent conductive materialif the display device is of a top emission type and may be made of areflective conductive material if the display device is of a bottomemission type. The transparent conductive material may be, but is notlimited to, indium tin oxide (ITO), indium zinc oxide (IZO), etc. Thereflective conductive material may be, but is not limited to, Al, Ag,Au, Pt or Cu. The pixel electrode PE made of the reflective conductivematerial may be made up of a single layer including the reflectiveconductive material or multiple layers formed by stacking the singlelayer one on another.

The common electrode CE electrically connects the second electrode E2 ofthe LED element 150 with the common power line CPL and may be defined asa cathode electrode. The common electrode CE is disposed on the frontsurface of the planarization layers 115-1 and 115-2 overlapping thecommon power line CPL while overlapping the second electrode E2 of theLED element 150. The common electrode CE may be made of the samematerial as the pixel electrode PE.

According to an exemplary embodiment of the present disclosure, one sideof the common electrode CE is electrically connected to the common powerline CPL through a second circuit contact hole CCH2 formed in the gateinsulating layer 112, the passivation layer 113 and planarization layers115-1 and 115-2 overlapping the common power line CPL. The other side ofthe common electrode CE is electrically connected to the secondelectrode E2 of the LED element 150 through an electrode contact holeECH formed in the planarization layers 115-1 and 115-2 overlapping thesecond electrode E2 of the LED element 150. Accordingly, the secondelectrode E2 of the LED element 150 is electrically connected to thecommon power line CPL through the common electrode CE.

According to an exemplary embodiment of the present disclosure, thepixel electrode PE and the common electrode CE may be formed together byan electrode patterning process using a deposition process to deposit anelectrode material on the planarization layers 115-1 and 115-2 includingthe first and second circuit contact holes CCH1 and CCH2 and theelectrode contact hole ECH, a photolithography process and an etchprocess. Accordingly, according to an exemplary embodiment of thepresent disclosure, the pixel electrode PE and the common electrode CEconnecting the LED element 150 to the pixel circuit PC can be disposedat the same time, such that the electrode connecting process can besimplified. In addition, the processing time for connecting the LEDelement 150 to the pixel circuit PC can be greatly shortened and theproductivity of the display device can be improved.

According to an exemplary embodiment of the present disclosure, thedisplay device further includes a transparent buffer layer 116.

The transparent buffer layer 116 is disposed on the substrate 110 suchthat it covers the entirety of the planarization layers 115-1 and 115-2with the pixel electrode PE and the common electrode CE, to form a flatsurface over the planarization layers 115-1 and 115-2 and protect theLED element 150 and the pixel circuit PC from an external impact.Accordingly, the pixel electrode PE and the common electrode CE aredisposed between the planarization layers 115-1 and 115-2 and thetransparent buffer layer 116. According to an exemplary embodiment ofthe present disclosure, the transparent buffer layer 116 may be, but isnot limited to, an optical clear adhesive (OCA) or an optical clearresin (OCR).

According to an exemplary embodiment of the present disclosure, thedisplay device further includes a reflective layer 111 disposed underthe emission region of each of the sub-pixels SP.

The reflective layer 111 is disposed on the substrate 110 such that itoverlaps with the emission region including the LED element 150. Thereflective layer 111 according to an exemplary embodiment of the presentdisclosure may be, but is not limited to being, formed of the samematerial as the gate electrode GE of the driving thin-film transistor T2and disposed on the same layer as the gate electrode GE. The reflectivelayer 111 may be formed of the same material as one of the electrodes ofthe driving thin-film transistor T2.

The reflective layer 111 reflects the light incident from the LEDelement 150 back to the above of the LED element 150. Accordingly, thedisplay device according to the exemplary embodiment of the presentdisclosure including the reflective layer 111 has a top emissionstructure. However, when the display device according to an exemplaryembodiment of the present disclosure has a bottom emission structure,the reflective layer 111 may be omitted or disposed on the above the LEDelement 150.

Optionally, the reflective layer 111 may be formed of the same materialas the source electrode SE/the drain electrode DE of the drivingthin-film transistor T2 and disposed on the same layer as the sourceelectrode SE/the drain electrode DE.

In the display device according to an exemplary embodiment of thepresent disclosure, the LED element 150 mounted in each of thesub-pixels SP may be disposed on a part of the adhesive member 114 abovethe reflective layer 111

The adhesive member 114 primarily fixes the LED element 150 of each ofthe sub-pixels SP. According to an exemplary embodiment of the presentdisclosure, the adhesive member 114 is in contact with the bottom of theLED element 150. It prevents the dislocation of the LED element 150during the mounting process and can facilitate the LED element 150smoothly separated from an intermediate substrate used fortransplanting, thereby minimizing defects in the process oftransplanting the LED element 150.

According to an exemplary embodiment of the present disclosure, theadhesive member 114 may be attached under the LED element 150 by beingdotted on each of the sub-pixels SP and spread by the pressing forceapplied in the mounting process of the light-emitting device.Accordingly, the position of the LED element 150 can be primarily fixedby the adhesive member 114. Therefore, according to the exemplaryembodiment of the present disclosure, the mounting process of thelight-emitting device is performed by simply attaching the LED element150 to the surface, so that the time taken for the mounting process ofthe light-emitting device can be greatly shortened.

The adhesive member 114 is interposed between the passivation layer 113and the planarization layers 115-1 and 115-2 and interposed between theLED element 150 and the passivation layer 113. According to anotherexample, the adhesive member 114 is coated on the entire surface of thepassivation layer 113 generally at an even thickness, but a part of theadhesive member 114 where contact holes are to be formed may be removedwhen the contact holes are formed. Accordingly, according to anexemplary embodiment of the present disclosure, the adhesive member 114is coated on the entire front surface of the passivation layer 113 at aneven thickness immediately before the mounting process of thelight-emitting device, thereby shortening the processing time fordisposing the adhesive member 114.

According to an exemplary embodiment of the present disclosure, theadhesive member 114 is disposed over the entire front surface of thepassivation layer 113, such that the planarization layers 115-1 and115-2 of this example cover the adhesive member 114.

According to another exemplary embodiment of the present disclosure,there is a recess for separately accommodating the LED element 150,which may be attached inside the recess by the adhesive member 114.However, the recess for accommodating the LED element 150 describedabove may be eliminated depending on process conditions for implementingthe display device.

According to an exemplary embodiment of the present disclosure, themounting process of the light-emitting device may include a process ofmounting a red light-emitting device in each of the red sub-pixels SP1,a process of mounting a green light-emitting device in each of the greensub-pixels SP2, and a process of mounting a blue light-emitting devicein each of the blue sub-pixels SP3, and may further include a process ofmounting a white light-emitting device in each of the white sub-pixels.

According to an exemplary embodiment of the present disclosure, themounting process may include only a process of mounting a whitelight-emitting device in each of the sub pixels. In this case, thesubstrate 110 includes a color filter layer overlapping each sub-pixel.The color filter layer transmits only light having a wavelength of acolor corresponding to the respective sub-pixel among the white light.

According to an exemplary embodiment of the present disclosure, themounting process may include only a process of mounting a light-emittingdevice of a first color in each of the sub-pixels. In this case, thesubstrate 110 includes a wavelength converting layer and a color filterlayer overlapping each sub-pixel. The wavelength converting layer emitslight of a second color based on a part of the light of the first colorincident from the light-emitting device. The color filter layertransmits only light having a wavelength of a color corresponding to therespective sub-pixel among the white light produced from mixture of thelight of the first color and the light of the second color. The firstcolor may be blue and the second color may be yellow. The wavelengthconverting layer may include a phosphor or quantum dots that emits thelight of the second color based on the light of the first color.

FIGS. 4A and 4B are plan views illustrating a light-emitting deviceaccording to an exemplary embodiment of the present disclosure.Description will be made with reference to FIGS. 4A and 4B inconjunction with FIGS. 1 to 3.

According to an exemplary embodiment of the present disclosure, an LEDelement 150 includes an emission layer EL, a first electrode E1, asecond electrode E2, and a structure 154. The emission layer EL includesa first semiconductor layer 151, an active layer 152 and a secondsemiconductor layer 152. The LED element 150 emits light as electronsand holes recombine according to the current flowing between the firstelectrode E1 and the second electrode E2.

The first semiconductor layer 151 may be a p-type semiconductor layerand the second semiconductor layer 153 may be an n-type semiconductorlayer, respectively. In the following description, they are referred toas the first and second semiconductor layers 151 and 153, forconvenience of illustration. In addition, the first electrode E1 and thesecond electrode E2 may be referred to as a p-type electrode or ann-type electrode depending on the electrical connection relation, i.e.,depending on a semiconductor layer which forms the electricalconnection. However, they may be referred to as the first electrode andthe second electrode, respectively, for convenience of illustration. Inaddition, in the following description, the first semiconductor layer151 and the second semiconductor layer 153 will be described as a p-typesemiconductor layer and an n-type semiconductor layer, respectively. Onthe contrary, the first semiconductor layer 151 and the secondsemiconductor layer 153 may be an n-type semiconductor layer and ap-type semiconductor layer, respectively.

The first semiconductor layer 151 is disposed on the active layer 152 toprovide holes into the active layer 152. According to an exemplaryembodiment of the present disclosure, the first semiconductor layer 153may be made of a p-GaN semiconductor material. The p-GaN semiconductormaterial may be GaN, AlGaN, InGaN, or AlInGaN. As the impurities usedfor doping the second semiconductor layer 153, Mg, Zn, Be, etc. may beused.

The second semiconductor layer 153 provides electrons into the activelayer 152. According to an exemplary embodiment of the presentdisclosure, the second semiconductor layer 153 may be made of a n-GaNsemiconductor material. The n-GaN semiconductor material may be GaN,AlGaN, InGaN, or AlInGaN. As impurities used for doping the secondsemiconductor layer 151, Si, Ge, Se, Te, C, etc. may be used.

The active layer 152 is disposed on the second semiconductor layer 153.The active layer 152 has a multi-quantum well (MQW) structure having awell layer and a barrier layer having a higher bandgap than that of thewell layer. According to an exemplary embodiment of the presentdisclosure, the active layer 152 may have a multiple quantum wellstructure such as InGaN/GaN.

The first electrode E1 is electrically connected to the firstsemiconductor layer 151 and is connected to the drain electrode DE orthe source electrode SE of the driving transistor T2 as a driving thinfilm pixel. The second electrode E2 is connected to the common powerline CPL.

The first electrode E1 may be a p-type electrode, and the secondelectrode E2 may be an n-type electrode. The type of the first electrodeE1 and the second electrode E2 may be determined depending on whetherthey supply electrons or holes, i.e., whether they are electricallyconnected to the p-type semiconductor layer or the n-type semiconductorlayer. In the following description, however, they are referred to asthe first electrode E1 and the second electrode E2 for convenience ofillustration.

Each of the first and second electrodes E1 and E2 according to anexemplary embodiment of the present disclosure may be made of a metalmaterial such as Au, W, Pt, Si, Ir, Ag, Cu, Ni, Ti or Cr or at least onealloy thereof. According to another exemplary embodiment of the presentdisclosure, each of the first and second electrodes E1 and E2 may bemade of a transparent conductive material. The transparent conductivematerial may be, but is not limited to, indium tin oxide (ITO) or indiumzinc oxide (IZO).

A structure 154 is disposed between the first electrode E1 and thesecond electrode E2 on the same plane. The structure 154 may be formedof an insulating material composed of an organic material or aninorganic material and may be disposed such that it overlaps with atleast a part of the first electrode E1 or the second electrode E2.

As described above, the structure 154 is disposed such that it overlapswith a part of the selected one of the first electrode E1 and the secondelectrode E2. One side surface of the structure 154 is disposed suchthat the first electrode E1 or the second electrode E2 is open. That isto say, the structure 154 is disposed between the first electrode E1 andthe second electrode E2 such that it covers a certain portion of one orboth of the first electrode E1 and the second electrode E2.

At least one side surface of the structure 154 has an inverted tapershape, such that the side surface that is in contact with the firstelectrode E1 or the second electrode E2 or both side surfaces may havean inverted taper shape.

The inverted taper shape of the structure 154 is to prevent ashort-circuit that may be occurred if the LED element 150 is notcorrectly disposed due to a processing error during a process ofdisposing the pixel electrode PE and the common electrode CE so that thefirst electrode E1 and the second electrode E2 are electricallyconnected to the pixel electrode PE or the common electrode CE. The stepcoverage of the pixel electrode PE and the common electrode CE cannot becontinued along the side surface of the inverted taper structure 154.Accordingly, it is possible to minimize a short circuit from beingoccurred between the first electrode E1 and the second electrode E2. Amore detailed description thereon will be given below.

According to an exemplary embodiment of the present disclosure, aninsulating layer made of SiO₂ or SiNx is disposed to cover the LEDelement 150 so that the first semiconductor layer 151, the active layer152 and the second semiconductor layer 153 is not exposed.

In addition, the second semiconductor layer 153, the active layer 152and the first semiconductor layer 151 may be sequentially stacked on asemiconductor substrate to form the LED element 150. The semiconductorsubstrate includes a semiconductor material such as a sapphire substrateor a silicon substrate. This semiconductor substrate may be used as asubstrate for growing each of the second semiconductor layer 153, theactive layer 152 and the first semiconductor layer 151, and then may beseparated from the second semiconductor layer 153 via a substrateseparating process. The substrate separating process may be a laserlift-off or chemical lift-off process. Accordingly, as the semiconductorsubstrate for growth is removed from the LED element 150, the LEDelement 150 may have a relatively small thickness and may beaccommodated in each sub-pixel SP.

FIGS. 5A and 5B are views for illustrating connection of electrodes of alight-emitting device according to an exemplary embodiment of thepresent disclosure.

Referring to FIGS. 5A and 5B in conjunction with FIGS. 1 to 4, astructure 160 may not be disposed inside the LED element 150. Thestructure 160 may not be formed together with the LED element 150, butmay be disposed on the LED element 150 after the LED element 150 havebeen disposed on the substrate 110.

A reflective electrode 111 is disposed on the substrate 110. Thereflective electrode 111 may be made of a metal having a highreflectivity to increase luminous efficiency by reflecting light emittedfrom the LED element 150, and may be disposed at a different position ormay be eliminated depending on the type of display device including theLED element 150.

A passivation layer 113 may be disposed on the reflective electrode 111.An adhesive member 114 may be disposed on the passivation layer 113. Thepassivation layer 113 may protect the driving elements which arethin-film transistors disposed on the substrate 110 or various wiringelectrodes and may provide a flat surface for disposing the LED element150.

The LED element 150 is disposed on the adhesive member 114. The adhesivemember 114 provides an adhesive force that allows the LED element 150 tobe smoothly transferred from an intermediate transfer substrate to thesubstrate 110.

After the LED element 150 is disposed, a planarization layer 115 isdisposed to fix the LED element 150, to connect the first electrode E1and the second electrode E2 with the pixel electrode PE and the commonelectrode CE.

The structure 160 may be made of the same material as the planarizationlayer 115 and may be made of an insulating material such as a bank layerthat may be disposed on the planarization layer 115. For example, thebank layer may be made of an organic insulating material such asbenzocyclobutene, polyimide, and photoacryl. The structure 160 may be aninorganic insulator made of an inorganic material.

The structure 160 may be formed on the LED element 150 when the LEDelement 150 is formed on the semiconductor substrate. However,considering that one or more transfer processes are involved for thesake of process convenience, the LED element 150 may be disposed on thesubstrate 110 and then the structure 160 may be disposed on the LEDelement 150 separately.

FIGS. 6A to 6D are cross-sectional views for illustrating electrodeconnection of a light-emitting device according to various exemplaryembodiments of the present disclosure. Various exemplary embodiments ofa display device having a structure will be described with reference toFIGS. 6A to 6D in conjunction with FIGS. 1 to 5.

In the above-described structure, the structure 154 may be integratedwith the LED element 150 or the structure 160 may be formed and disposedafter the LED element 150 is disposed on the substrate 110.

In the display device 100 including the structures 154 and 160 shown inFIG. 6A, the first electrode E1 is connected to the pixel electrode PEand the second electrode E2 is electrically connected to the commonelectrode CE in the electrode contact hole (ECH) region of the LEDelement 150. The structures 154 and 160 are disposed between the firstelectrode E1 and the second electrode E2 and have a region overlappingthe first electrode E1 and/or the second electrode E2. The structures154 and 160 have an inverted taper shape with faces adjacent to thefirst electrode E1 or the second electrode E2.

If the LED element 150 is disposed on a location of the substrate 110 asdesigned, the possibility that a short-circuit is occurred between thefirst electrode E1 and the second electrode E2 when the pixel element PEand the common electrode CE are disposed is lowered.

FIG. 6B shows an example where the LED element 150 is misaligned awayfrom the location of the substrate 110 due to an error or other externalissues during a disposing process. When this happens, the firstelectrode E1 is covered by the pixel electrode PE when the pixelelectrode PE is disposed through the electrode contact hole ECH, and thepixel electrode PE overlaps with the second electrode at least partiallydue to the misalignment.

The structure 160 electrically insulates the pixel electrode PE from thesecond electrode E2, such that it is possible to minimize the electrodeconnection defect to prevent both the first electrode E1 and the secondelectrode E2 from being electrically connected to the pixel electrodePE. Alternatively, it is possible to minimize the defect that both thefirst electrode E1 and the second electrode E2 are connected to thecommon electrode CE.

That is, the display device 100 including the structure 160 can have amore flexible and highly reliable structure with respect to a processingerror in disposing the LED element 150.

Referring to FIG. 6C, the LED element 150 includes the structure 154.Similarly to the example shown in FIG. 6B, when the LED element 150 ismisaligned away from the location due to a processing error or the like,the structure 154 insulates the pixel electrode PE from the secondelectrode E2. As a result, it is possible to minimize the electrodeconnection defect to prevent both the first electrode E1 and the secondelectrode E2 from being electrically connected to the pixel electrode PEsimultaneously.

Finally, referring to FIG. 6D, the pixel electrode PE and the commonelectrode CE are electrically connected to the first electrode E1 andthe second electrode E2 through the electrode contact hole ECH, and thepixel electrode PE and the common electrode CE should not beelectrically connected to each other. However, when the size of the LEDelement 150 is very small, such as a few tens of micrometers or less, adefect that the pixel electrode PE is connected to the common electrodeCE may occur.

Referring to FIG. 6A to FIG. 6D, the pixel electrode PE or the commonelectrode CE may be formed to be extend over the structure. The pixelelectrodes PE connected to the first electrode E1 and the pixelelectrodes PE extended over the structure 154 and 160 may beelectrically disconnected to each other by the structure 154 and 160having an inverted taper shape. The common electrode CE connected to thesecond electrode E2 and the common electrode CE extended over thestructure 154 and 160 may be electrically disconnected to each other bythe structure 154 and 160 having an inverted taper shape.

The structure 160 has an inverted taper shape, and the side adjacent tothe first electrode E1 or the second electrode E2 has an inverted tapershape. Therefore, since the conductive material having a low stepcoverage is used in the process of disposing the pixel electrode PE andthe common electrode CE, the electrical connection at the side of thestructure 160 is naturally disconnected.

By virtue of the structure 160 having the inverted taper shape, it ispossible to minimize defects that the pixel electrode PE is electricallyconnected to the common electrode CE, so that process stability can beimproved and product reliability can be increased.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the light-emitting deviceand the display device using the same of the present disclosure withoutdeparting from the technical idea or scope of the disclosure. Thus, itis intended that the present disclosure cover the modifications andvariations of this disclosure provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An LED element comprising an n-type semiconductorlayer and a p-type semiconductor layer, comprising: an n-type electrodeconnected to the n-type semiconductor layer; a p-type electrodeconnected to the p-type semiconductor layer; and a structure disposedbetween the n-type electrode and the p-type electrode to separate then-type electrode and the p-type electrode not overlapping each other,wherein a side surface of the structure adjacent to the p-type electrodeor the n-type electrode has an inverted taper shape, such that a topsurface, furthest from the n-type semiconductor layer, has a widercross-section than any lower cross-section of the structure, and whereinthe structure covers and directly contacts an edge of the n-typeelectrode and/or the p-type electrode.
 2. The LED element of claim 1,wherein: an angle between the side surface of the structure and a topsurface of the n-type electrode, directly below the side surface of thestructure, has an acute angle; and an angle between the side surface ofthe structure and a top surface of the p-type electrode, directly belowthe side surface of the structure, has an acute angle.
 3. The LEDelement of claim 1, wherein the p-type electrode, the n-type electrode,or at least one of each of the p-type electrode and the n-type electrodeare on a same plane with the structure.
 4. The LED element of claim 1,wherein the structure is made of an insulating material.
 5. A displaydevice, comprising: an LED element disposed on a substrate, the LEDelement comprising an n-type electrode and a p-type electrode; a pixelelectrode disposed on the substrate and connected to the p-typeelectrode; a common electrode disposed on the substrate and connected tothe n-type electrode; and a structure disposed between the n-typeelectrode and the p-type electrode to separate the n-type electrode andthe p-type electrode not overlapping each other, wherein a side surfaceof the structure adjacent to the p-type electrode or the n-typeelectrode has an inverted taper shape, such that a top surface, furthestfrom the n-type semiconductor layer, has a wider cross-section than anylower cross-section of the structure, and wherein the structure coversand directly contacts an edge of the n-type electrode and/or the p-typeelectrode.
 6. The display device of claim 5, wherein: an angle betweenthe side surface of the structure and a top surface of the n-typeelectrode, directly below the side surface of the structure, has anacute angle; and an angle between the side surface of the structure anda top surface of the p-type electrode, directly below the side surfaceof the structure, has an acute angle.
 7. The display device of claim 5,wherein the structure is disposed such that it overlaps with the p-typeelectrode and/or the n-type electrode.
 8. The display device of claim 5,wherein: the substrate comprises at least one driving element; and thepixel electrode is connected to the driving element.
 9. The displaydevice of claim 5, wherein a thickness of the structure is thicker thana thickness of the n-type electrode or the p-type electrode to have theinverted taper shape.
 10. The display device of claim 5, wherein thepixel electrode contacts to the side surface of the structure adjacentto the p-type electrode, or the common electrode contacts to the sidesurface of the structure adjacent to the n-type electrode.
 11. Thedisplay device of claim 5, wherein the pixel electrode and the commonelectrode are conductive material having a low step coverage enough tobe disconnected by the inverted taper shape of the structure.